I been searching most of the day and even on this forum and the funny thing is I actually found the solution by clicking on a related tab from my topic. This is what I did.
RetroArch Quick Menu while in game > options :
display MAME menu : OFF (if selected the tab menu will not close)
legacy Remapping : actived
May be
input interface : simultaneus (keyboard & retropad)
Already checked that link before. Did not have the info I was looking for but thank you for responding.
When I use MAME 2003-Plus as my core for any rom game it does not give me the option to bring up the dip switch setting via the tab button. Pressing the TAB button does nothing. Now the TAB button does work in MAME 2003. Does not the recalbox version of MAME 2003-Plus allow the TAB button?